lecture 9/10- canine virology Flashcards
what is the family and subfamily of canine herpes virus 1?
family: Herpesviridae
subfamily: Alphaherpesvirinae
you are presented with an adult dog who has mild rhinitis, vesicular vaginitis, and posthitis. the owner describes these signs as “on and off”.
what is your top differential?
canine herpes virus 1
what happens when a pregnant dog is infected with herpes virus?
early fetal loss, late term abortion, stillbirth, or birth of compromised neonates
you suspect canine herpes virus 1 in a neonatal dog that you are doing a necropsy on. what is a pathognomonic sign that you would expect to see grossly and histologically on the kidneys?
petechiae in renal cortex and radiating hemorrhage of renal pelvis.
histo: eosinophilic intracellular inclusions and tubular necrosis of parenchyma (this is in lungs too)
what organs show gross lesions when a dog is infected with canine herpes virus? what are the gross lesions?
kidney- petechiae / hemorrhage, necrosis
liver- necrosis and hemorrhage
lung- necrotizing interstitial pneumonitis
eyes- diffuse corneal oedema and mature cataract
brain- viral staining on histo
true or false: lesions of herpes virus in adult dogs are pathognomonic
false- pathognomonic in neonates
what does canine herpes virus look like histologically
Epithelial cells contain round, eosinophilic, intranuclear inclusion bodies surrounded by a clear halo and marginated chromatin
is there a vaccine for canine herpes?
nope
can colostrum protect puppy from herpesvirus ?
yes
how do adult dogs become infected with herpesvirus?
sexual or respiratory transmission
how do neonate dogs become infected with herpesvirus?
ingestion, inhalation, birth canal, contact, fomites
how can fetuses become infected with canine herpesvirus?
in utero
what is the structure and replication strat of canine herpes
enveloped ds DNA
what family and genus is infectious canine hepatitis (ICH) a part of?
family: adenoviridae
genus: mastadenovirus
what is the structure and replication strategy of infectious canine hepatitis ?
naked (with projecting fibres), dsDNA
which adenovirus is responsible for ICH?
CAV-1
what do the fibres on adenoviruses do?
- hemagglutinating activity
- mediate attachment of virus to cellular receptors
in what part of a cell do adenoviruses replicate?
nuclei
what is ICH susceptible to? what is it not susceptible to ?
susceptible to: iodine, phenol, sodium hydroxide, and heating for 5 mins
stable in environment (naked virus!)
which dogs are at risk of disease associated with ICH?
under one year or unvaccinated
during the acute phase of viral transmission of ICH, virus is excreted in ______, _____, and ______.
how long is the acute phase?
saliva, feces, and respiratory mucus
5-10 days
during the chronic phase of viral transmission of ICH, virus is excreted in ______.
how long is the chronic phase?
urine
10-14 days for up to 6-9 months
how is ICH transmitted?
contact with fomites, oronasal exposure, ectoparasites and vectors
what type of hypersensitivity is an arthus reaction? what canine disease is associated with this?
type 3 hypersensitivy
associated with infectious canine hepatitis
true or false: canine hepatitis is commonly spread through aerosols
false- this is unlikely. more likely contact with fomites, oronasal exposure, or ectoparasites
how does type 3 hypersensitivity cause pathogenesis in blood vessels?
- increased vascular permeability
- immunocomplexes deposit on blood vessel wall
- platelet aggregation and compliment activation
- neutrophils come…
- damage to vessel wall
during the cytopathic phase of ICH, where do viruses replicate? what pathogenisis does each cause? (3)
hepatocytes- acute hepatitis, incracellular inclusions, chronic hepatitis persist…
renal tubule cells- nephritis, virus shed in urine
vascular endothelial cells- hemorrhage, DIC, intranuclear inclusions
circulating immune complexes of ICH deposit in… which leads to…
deposition in renal glomeruli-glomerulonephritis
local immunocomplexes of ICH lead to…
corneal edema, opacity, and anterior uveitis (blue eyes!)
a dog presents with a slight fever, lethargy, mucous membrane congestion, tendor abdomen, jaundice, and vomiting. he also has significant cataract. what is a disease you might be worried about?
infectious canine hepatitis
why do dogs with ICH sometimes get blue eyes? does it go away?
type 3 hypersensitivity reaction/arthus reaction
resolves spontaneously
you are doing a necropsy on a dog and find the following gross lesions:
- multifocal lung hemorrhages
- thickened and enlarged gallbladder
- segmental hemorrhagic enteritis
- hemorrhagic lymph nodes
- hemorrhage on oral mucosa
- enlarged liver (friable and yellow discoloration)
- brain hemorrhage
what is a virus you are worried about
ICH
what does ICH look like on histo
basophilic intracellular inclusions surrounded by a clear zone
centrilobular necrosis
clinically, how would you diagnose ICH?
consider clinical signs, hematological findings, liver enzyme (increase ALT)
what role to wild carnivores play in regard to ICH spread?
they are reservoirs for the virus , but are often subclinical (still spreading!!)
does maternal immunity protect against ICH? for how long?
yes for 5-7 weeks, but by 14-16 weeks wane completely
so how do we control ICH?
environmental control - this is tough tho because virus is naked (can use iodine, phenol, sodium hydroxide, and heating)
control vectors - wild carnivores and ectoparasites
vaccinate!!
what are the vaccine options for ICH?
what is something to note about modern vaccines
killed vaccines for CAV-1
modified live vaccines for CAV-1
modified live vaccines for CAV-2
modern modified live vaccines contain either CAV-1 or CAV-2, but either protects against hepatitis and cough. note these vaccines each have pros and cons
what is kennel cough now known as
canine respiratory disease complex or canine infectious tracheobronchitis
what is the viral etiology of of CRDC? 3
canine parainfluenza virus (common)
canine adenovirus 2
canine distemper virus
what is the common bacterial etiology of CRDC?
Bordetella bronchiseptica
how are viruses associated with CRDC transmitted?
viruses shed in ocular and respiratory secretions (aerosolized microdroplets, direct contact, fomites)
how long are viruses associated with CRDC shed following infection?
8-10 days
where do CRDC viruses replicate
respiratory epithelium
an adult dog presents with a harsh dry honking cough, watery nasal discharge, pharyngitis, and tonsilitis, BUT is not systemically ill
what are you worried about?
uncomplicated CRDC/canine infectious tracheobronchitis
viruses are: CPiV, CAV-2, CDV
bacteria: B. bronchiseptica
you are presented with a young unvaccinated pup (or immunocomp or elderly) who has had respiratory signs over the last few days, but has now progressed to being lethargic, has a severe fever, and is inapp.
what are you worried about?
complicated CRDC/canine infectious tracheobronchitis
need to treat!
what vaccines are there for CRDC/kennel cough/CIT
- modified live virus vaccines for distemper, CPiV, and CAV-2 (also protects against CAV-1)
- also Bordetella vaccine!
- also combo of bordetella and parainfluenza (intranasal)
what family is canine influenza a part of? which type of influenza is it
orthomyxoviridae
type A influenza
explain how antigenic drift has influenced influenza in dogs. be specific about the strain (H__N__)
equine H3N8 mutated and became infectious to dogs (antigenic drift). now this virus is capable of spreading among the canine population
where does canine influenza replicate
epithelial cells of respiratory tract (ciliary shafts) and alveolar macrophages
what is H5N1? how does it relate to canine influenza
highly pathogenic avian influenza
there have been a couple of cases of dogs eating raw bird meat and becoming infected with H5N1. these dogs do get sick and some die
what kind of virus is canine distemper virus
Morbillivirus
who can be infected by canine distemper?
so many animals !
what is the primary reservoir for canine distemper virus
unvaccinated dogs (including feral)
how many serotypes of CDV are there?
1
where does variation of CDV occur, genetically
H-gene variation leads to several genotypes
what are acute signs of CDV?
fever, conjunctivitis, anorexia, V+, D+
where does CDV replicate
lymph organs
what are chronic signs of CDV?
ataxia, tremors, mycoclonus, seizures, moribund
what fluids/exudates contain CDV
respiratory, ocular, urine, feces, skin, etc
where does CDV initially replicate?
oral pharynx
if there is no antibody response to CDV, what happens to the dog?
severe, multisystemic illness
virus persists in tissues
death or recover with CNS signs
what body systems are impacted by CVD?
GI, CNS, respiratory
if a dogs’ CNS is infected with CVD what is its prognosis? what are 4 possible outcomes?
poor prognosis
4 outcomes are:
- seizures, mycoclonus, death
- old dog encephalitis
- hard pad disease, death
- few recover
what is the prognosis of a dog who is infected with the GI form of CDV? what are the clinical signs
good prognosis (some do die tho)
watery D+, V+
what is the prognosis of a dog who is infected with the respiratory form of CDV? what are the clinical signs
good prognosis
coughing, pneumonia
can CDV be subclinical?
yes!
enamel hypoplasia is a sign of which canine virus? why?
CDV in dogs less than 6 months old
ameloblasts are still producing enamel at this point soo direct viral infection destroys ameloblasts and leads to enamel hypoplasia in developing teeth
what is hard pad dz? which virus is it associated with? what form?
hyperkeratosis of foot pads
associated with CDV and often accompanies neurological distemper
hard pad dz is likely caused by an up regulation of ____
cytokeratin
what does histo look like on a dog with hard pad disease? what virus causes this
hyperplastic epithelium with inclusion bodies
caused by CDV
where are inclusion bodies found with CDV?
nucleus AND cytoplasm
what is seen histologically with CDV in the brain? 3 things
intranuclear and intracytoplasmic inclusion bodies
perivascular cuffing
demyelination
should we worry about CDV in wildlife populations?
yes!!
can you use PCR to diagnose CDV?
nooo RT-PCR
what is the problem with using serological assays to diagnose CDV?
we vaccinate against it in domestic dogs - so hard to distinguish between acquired CDV and vaccine induced immune response
what is a positive and 2 negatives associated with the live attenuated and modified CDV vaccines? are there other options?
pos: long lasting immunity
con: not for immunosuppressed or pregnant animal, can be fatal in mink and ferrets
there are also recombinant canarypox vectored vaccines and inactivated vaccines
what animals are resistant to rabies
birds, amphibians, and reptiles
what is replication strat and structure of rabies
-ss RNA, enveloped
what family and genus is rabies a part of
rhabdoviridae
Lyssavirus
what is the geological distribution of rabies
everywhere except new zealand!
what are the reservoirs for rabies in Canada?
bats, skunks, raccoons, foxes
how is rabies transmitted?
saliva, cerebrospinal fluid, infected neural tissues
for how long do animals excrete rabies virus before clinical signs? cats, cattle, skunks/bats, dogs
cats- 1-5 days
cattle- 1-2 days
skunks and bats- up to 14 days
dogs- 1-5 days
what is the pathogenesis of rabies virus?
1- bite
2- virus in muscle
3- in synaptic cleft
4- anterograde transport of virus towards neural body
5- spinal cord
6- salivary gland
what are the two forms of rabies clinical manifestation ? what animals get each ? who gets both
furious form- cats
paralytic form- horses, cattle, bats
both- dogs
does rabies always result in death
yes
what are negril bodies? which virus gets these?
intracytoplasmic inclusion bodies that are found in nerve cells of medulla and other ganglia
rabieeesss
you are doing a necropsy on the brain of a dog and find hemorrhage, negril bodies, perivascular cuffs, and degenerating neurons. what should you probably be suspicious of?
rabies
how is rabies diagnosed? who does it? what test is best?
need to identify virus in brain tissue (medulla oblongata and cerebellum)
CFIA does this
test- direct fluorescent antibody test
what vaccine options are there for rabies
modified live, recomb, inactivated
can wildlife be vaccinated for rabies? how is this done
what are the issues?
oral vaccines used to control rabies in foxes, coyotes, and raccoons
cannot control dose, cannot guarantee non-targeted animals won’t eat them, displacement
what are the core vaccines for dogs
canine distemper
infectious canine hepatitis
canine parvovirus
rabies
what are the non-core vaccines for dogs
bordetellosis
canine parainfluenza virus
leptospirosis
borreliosis (lyme)
coronavirus
what are the top 3 canine viruses that cause enteritis
rotavirus
coronavirus
parvovirus
what is the structure and replication style of parvovirus
naked ssDNA
what is the structure and replication style of rotavirus
naked dsDNA
what is the structure and replication style of coronavirus
enveloped ss RNA
what family is canine parvo in
parvoviridae
what are the two types of canine parvovirus
CPV-1: minute virus of canines
CPV-2: has two antigen types (a and B)
how is canine parvo transmitted
fecal-oral
indirect with fomites
what are 3 manifestations of canine parvo
lymphopenia
enteritis
neonatal myocarditis
can parvovirus go to placenta in dogs? how does this impact the fetus?
yes- can lead to myocarditis (which leads to sudden death or CHF then death)
what cells do canine parvo virus infect
crypt cells (stem cells- actively dividing)
why does canine parvo need to target cells that are actively dividing
unlike other DNA viruses, parvoviruses are unable to switch on DNA synthesis in host cells
what happens if you vaccinate for canine parvo before window of susceptibility ?
when should we vaccinate then?
vaccine will neutralize maternal antibodies
vaccinate from 9 weeks to 16-20 weeks, 2-3 weeks apart
what is the family of CCoV
coronaviridae
what are the serotypes of CCoV
CCoV-I and CCoV-II
what is the replication strat and structure of CCoV
enveloped, positive sense ssRNA
how are CCoV and SARS-CoV related?
same family, dif genera (alpha in dogs, ___ fix this___ in covid pandemic)
what is seen grossly if a dog is infected with pantropic CCoV
lung- pneumonia in caudal lobe, fibrin
kidney- cortex hemorrhage, coagulative necrosis
what strain of coronavirus is associated with resp signs in dogs
canine respiratory coronavirus (CRCoV)
how is canine enteric corona transmitted
fecal oral route
what cells are targeted by canine corona? how does this effect functionality
mature enterocytes
become shorter –> nonfunctional
what is characteristic of canine corona, histologically
short villi
what color is D+ from canine corona
orange (versus bloody with parvo)
does canine coronavirus vaccine protect against resp and enteric corona?
no- just enteric
what family is rotavirus in
reoviridae
what is the structure and replication strat of canine rota
naked, dsRNA, segmented genome
how is canine rotavirus transmitted
fecal oral
what is seen histologically with canine rotavirus
immature enteroocytes (short villi)
what is the only virus which produces enterotoxins
rotavirus
what protein is responsible for enterochromaffin cell stimulation to make enterotoxins? what virus?
non structural protein 4 (NSP4)
canine rotavirus
is there a vaccine for canine rotavirus
nope
